What is the main control board backup board and protect-group of the OLT?

There is an OLT, originally a 2-slot backup, 3-slot main control board, and 0-3-0 as the upstream port. Now unplug slot 3, wait for slot 2 to activate the main control board and insert it back into slot 3, and insert the 0-3-0 optical module into slot 2. Then I log in to the OLT and find that the data automatically becomes port vlan zzzzzzz 0/ 2 0.

When the optical module is directly inserted into the current main control board, will the system automatically change the data?

If you want to switch between active and standby, besides unplugging the original main control board, is there any other easier way, such as logging in to the OLT to modify it? Will there be any adverse effects?

What's the role of protect-group? Can anyone explain the following as an example?

protect-group 10 protect-target as-mainboard workmode portstate

protect-group member board 0/9 role work

protect-group member board 0/10 role protect

protect-group enable

Thanks